Would Imperial Japan have crumbled if the US hadn't dropped the atomic bombs?

There were several comments, and I decided to try and reply to one of them - written by "Just Jennifer":

Like it, or not, the use of the atomic bomb, as horrible as they were, quickly ended the war. The alternative would have been a massive invasion of Japan, which would have resulted in far more death of Japanese soldiers and civilians. It is sad that all too often military leaders enter into wars that are paid for with civilian lives. This was especially true in World War II. At least in Japan, the Emperor did the right thing, and decided to end the war. In Germany, it was not the loss of civilian lives that resulted in surrender, but the simple fact that the military could no longer sustain a military effort.

This type of response tends to be a kind of standard response based on the received wisdom: "The atomic bombs ended the war. If we didn't drop the atomic bombs, the war would have dragged on, and we would have lost thousands more soldiers." I haven't really been one to buy into that line of reasoning, because it just didn't make sense: Japan was being bombarded daily, they were losing the island cordon that helped protect the home islands from direct naval attack, and their major ally - Nazi Germany - had just collapsed (meaning that the US could turn all of its attention on attacking Japan, and the USSR might do the same thing), never mind the fact that Imperial Japan hadn't had time to actually consolidate the massive land grabs that they had accomplished during the 1930s and early 1940s. It doesn't take a military genius to figure out that you would have to sue for peace as soon as possible, especially if you wanted to spend time consolodating your new empire. A part of my mind just couldn't accept that the entirety of the Japanese government was part of what would have amounted to a suicide cult hell-bent on preserving every tsubo of land. I mean, there's ideological fanaticism, but even that can't sustain you against plain and simple facts.

And so, I looked at some of the other things that were going on in that theatre of war from December 7, 1941 through August 15, 1945, looking especially for what the Soviets were doing. There was a lot there that I never learned about in history classes (for whatever reason), and it appeared to me that "Just Jennifer" didn't learn them - or was discounting them - in her response.

I therefore went about drafting a reply, but - when I hit "Publish", I received the notification that it must be at most 4096 characters, and so I post my thoughts on "Would Imperial Japan have crumbled if the US hadn't dropped the atomic bombs?" below:

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@Just Jennifer

As a national of both the US and Japan, I have to say that your points are true... but:

You forget (as many people seem to do) that the USSR and Japan had a de facto military detente since Japan's halted invasion of Mongolia in the 1939 (see the battle of Khalkhin Gol). Some say that this defeat - led by Soviet General Zhukov (the same Zhukov who would later lift the siege of Leningrad and lead the invasion of Berlin) - created a turning-point in the Imperial Japanese military strategy. In short, the Imperial Army lost political power (and their strategy of capturing Siberia all the way to Lake Baikal was scrapped) and the Imperial Navy won (and so Japan followed its coastal warfare strategy).

What does that have to do with the atomic bombing? Well, in 1941, Japan signed a neutrality pact with the USSR in order for both countries to focus on what they each saw as more "critical" issues (such as Soviet defense in western Russia and Japanese expansion in southern China). By 1945, however, the USSR felt that it didn't need to extend the neutrality pact (after all, it's position had been greatly strengthened, while Japan's was dissolving). Long story short, the USSR declared war on Japan a few hours before the end of August 8, 1945, and attacked along three different points in Japanese-controlled Manchuria.

Japan felt the first atomic strike on August 6, and merely hours after having war declared on it by the USSR, it felt the second atomic strike on August 9.

It was a pretty stark realization that Imperial Japan could not stand. (However, diehards did continue to try and do just that - instigating what is now known as the Kyujo Incident.) Japan went from hoping to sue for peace (while holding what it had gained since the turn of the 20th Century) to having to agree to the totality of the Potsdam Declaration (i.e., total surrender). In that way, it was analogous to Germany, save for being merely a few moves earlier in the "chess game": the military would soon be unable to sustain a military effort.

However, what about the "What if" scenario of a US land invasion? (Let's say that there were no atomic bombs.) The Japanese military disposition on August 9, 1945 - immediately after the declaration of war by the USSR - would be at the very point of breaking. If Japan wanted to defend the home islands, it would have had to executed a fighting retreat throughout China, Manchuria, and Korea, due to having to face a battle-hardened Soviet military that was far more advanced than the one that it had lost so disastrously to (indeed, the Soviet advances into Manchuria were quite decisive).

In short, the US and UK would not have had to lift the entire burden of an attack on Japan. The Soviets was apparently very happy to take advantage of a fast-crumbling Imperial Japan to try and stake out more satellite territory. I agree that the atomic bombing did end the war quickly, but without the atomic bomb, I doubt that the war would have lasted even months more: the writing was on the wall one way or another, and the only question for Imperial Japan was how much of their territory would they have to surrender to the US and the USSR.

To that end, I tend to fall in the camp of asking why not spend Little Boy on an island or a relatively uninhabited part of Japan? It's destructive capacity would have been noted just as visibly as it was on the bombing of Hiroshima. However, this didn't happen: Little Boy was dropped on Hiroshima on August 6, 1945, proving the deadly capacity of this weapon (and offering a very rude awakening to the massive leap in weapons technology that the US now possessed).

I also fall into the camp of people asking why we don't learn anything about the Soviet Union's impact on WWII. (There are too many Americans who think that the US invaded Berlin and killed Hitler; there are even more who don't know about the Neutrality pact nor about the Soviet declaration of war in August of 1945.) However, this is a problem of setting school curricula, and - at least in today's political landscape, in which school boards become the setting of intense political scrutiny - I don't think that this will really be rectified, and we will likely continue to receive responses that amount to the received wisdom.

In sum: as a national of both the US and Japan, I also grew up with very mixed feelings about World War 2, and having looked further than most US nationals tend to look at the question of the atomic bombs ending the war, I came up with the recognition that it wasn't as simple as, "if we didn't drop the bombs, it would have been so much worse." But then, again, extrapolating into an alternative history is merely taking (hopefully tenuous) steps into a dark tunnel: at some point, you end up just groping, hoping not to fall down.